Gas-insulated switchgear device

ABSTRACT

A gas-insulated switchgear device for high- and medium-voltage applications, comprising an enclosure which contains a disconnection unit which is electrically connected to a first electric terminal and is arranged in the enclosure in a substantially central position, and a first interruption unit and a second interruption unit which can be connected electrically to the disconnection unit and, respectively, to a second electric terminal and a third electric terminal, the first and second interruption units being arranged mutually opposite with respect to the disconnection unit.

BACKGROUND OF THE INVENTION

The present invention relates to a gas-insulated switchgear device forhigh- and medium-voltage applications, having improved functions andcharacteristics; the expression “high- and medium-voltage applications”is used to reference applications with operating voltages equal to orabove 1000 Volt.

In particular, the device according to the invention, by virtue of itsinnovative structure, allows to optimize execution of the requiredelectric maneuvers, according to a solution which is at once simple,effective and compact.

It is known from the art that electric switching operations, for bothinterruption and disconnection, in gas-insulated circuit breaker anddisconnector units are provided by virtue of the translatory motion ofone or more moving contacts which can couple/uncouple with respect tocorresponding fixed contacts. A significant drawback of known types ofdevices is the fact that the various switching operations, for examplefor disconnection on the input line or on the output line, are performedby means of dedicated components which are structurally separate andmutually distinct; in this way, the number of components used toimplement the various switching operations is large and entails anincrease in the space occupation and total volume of the device, with aconsequent cost increase.

Furthermore, the contacts are moved by using actuation devices whichgenerally comprise actuators of the mechanical or hydraulic type whichrequire complicated kinematic systems to transmit motion to the movingcontact. In particular, the disconnection maneuver requires thecoordinated movement of one or more moving contacts, so that theopening/closure of the disconnection contacts occurs in the intendedsequence. This usually entails complicated coupling mechanisms and/orcomplicated actuation and control systems, especially when disconnectionoccurs on multiple-bar systems. In view of the mechanical complexity ofthe movement elements and of the large number of components used,maintenance interventions are necessary in order to maintain nominalbehavior and ensure repeatability of performance.

This structural complexity has an even worse impact when the variouscircuit breaker and disconnector units are used to provide substations.An example in this regard is shown in FIG. 1, which schematicallyillustrates a minimal configuration of an electrical substation of thesingle distribution bar type. As shown in said figure, each phase of themain power line 101 is connected in input to a correspondingdistribution bar 100; at least one disconnector 102 and a currenttransformer 103 are used along the junction conductor that connects aphase of the line 101 to the corresponding bar 100. In turn, the bars100 are electrically connected to a power transformer 104, whichappropriately varies the voltage so as to obtain an adequate levelthereof in input to a set of medium-voltage devices, generallydesignated by the reference numeral 105; ahead of the power transformer104 there are also surge arresters 106 which protect the transformeragainst possible damage. A second disconnector 102, a second currenttransformer 103 and a circuit breaker 109 are used along the connectionbetween each bar 100 and the power transformer 104. In output from thesubstation, each bar 100 is connected to the corresponding phase of theline 101 according to an architecture which is similar to the inputarchitecture, i.e., by using another disconnector 102 and an additionalcurrent transformer 103.

In the most common applications, the minimum configuration of theelectrical substation is generally conveniently supplemented by usingadditional primary components; in particular, two voltage transformers,two disconnectors and two circuit breakers are used for each phase ofthe main power line 101, arranging them respectively at the inputconnection and in output between the line phase and the bar of thesubstation. The substation is furthermore equipped with a series ofsecondary components, constituted by protection and control systems, inorder to ensure the correct electrical operation of the system and avoiddangerous damage.

Owing to the large number of components required, even for the provisionof a minimal configuration, known types of substation are unsatisfactoryin practical use mainly due to their high cost, to their spaceoccupation requirements and to the need for frequent maintenance. Saidsubstations furthermore do not have a structure of the modular typewhich makes them conveniently flexible in their applications and easy toimplement according to the various application requirements.

SUMMARY OF THE INVENTION

The aim of the present invention is to provide a gas-insulatedswitchgear device for high- and medium-voltage applications which iscapable of integrating the functions that in the current art areperformed by multiple structurally mutually distinct components.

Within the scope of this aim, an object of the present invention is toprovide a gas-insulated switchgear device for high- and medium-voltageapplications which allows great flexibility and simplicity in theexecution of the required electric switching operations.

Another object of the present invention is to provide a gas-insulatedswitchgear device for high- and medium-voltage applications which has acompact structure and small dimensions, so as to significantly reducethe space occupation requirements.

Another object of the present invention is to provide a gas-insulatedswitchgear device for high- and medium-voltage applications which has areduced mechanical complexity.

Another object of the present invention is to provide a gas-insulatedswitchgear device for high- and medium-voltage applications which easilyallows to realize different application configurations, particularly forthe implementation of substations with a single and/or double conductingbar system.

Another object of the present invention is to provide a gas-insulatedswitchgear device for high- and medium-voltage applications which ishighly reliable, relatively easy to manufacture and at competitivecosts.

This aim, these objects and others which will become apparenthereinafter are achieved by a gas-insulated switchgear device for high-and medium-voltage applications, characterized in that it comprises anenclosure which contains a disconnection unit which is electricallyconnected to a first electric terminal and is arranged in the enclosurein a substantially central position, and a first interruption unit and asecond interruption unit which are connected electrically to thedisconnection unit and, respectively, to a second electric terminal anda third electric terminal, said first and second interruption unitsbeing arranged mutually opposite with respect to the disconnection unit.

The device according to the invention can be of the segregated-phase orjoined-phase type, for a single-bar or multiple-bar system, withsingle-pole or three-pole actuation.

The device according to the invention therefore has a compact structurewhich integrates, within a single body, both the circuit-breakingelements and the disconnection elements, according to a solution whichin any case allows to perform the required electrical switchingoperations simply and effectively.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will becomeapparent from the description of some preferred but not exclusiveembodiments of a switchgear device according to the invention,illustrated only by way of non-limitative example in the accompanyingdrawings, wherein:

FIG. 1 is a schematic view of a known type of electric powertransmission and distribution substation;

FIG. 2 is a view of the switchgear device according to the invention;

FIGS. 3a-3 f are schematic views of some possible electrical switchingoperations that can be performed with the device of FIG. 2;

FIGS. 4 and 5 are views of a possible embodiment of an electricsubstation with a three-phase single-bar system which uses the device ofFIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 2, the switchgear device according to theinvention, generally designated by the reference numeral 200, comprisesan enclosure 1 which contains an insulating gas and internallyaccommodates a first interruption unit 4, a second interruption unit 14and a disconnection unit 5. The disconnection unit 5 is electricallyconnected to a first electric terminal 2 and to the two interruptionunits 4 and 14 in the manner described hereinafter; in turn, theinterruption units 4 and 14 are electrically connected to a secondelectric terminal 11 and to a third electric terminal 13, respectively.In the embodiment shown in FIG. 2, the electric terminals 2, 11 and 13(which are partially visible in the figure) are accommodated incorresponding bushings, designated by the reference numerals 40, 41 and42 respectively, which are connected to the enclosure 1.

Advantageously, the disconnection unit 5 is arranged inside theenclosure 1 in a substantially central position, with the twointerruption units 4 and 14 arranged mutually opposite with respect tothe disconnection unit 5.

In particular, the interruption units 4 and 14 comprise an interruptionchamber 3 which accommodates a fixed contact 6 and a moving contact 7which is operatively controlled by actuation means; the moving contact 7of each one of the interruption units 4 and 14 is electrically connectedto the terminal 11 and to the terminal 13, respectively. The actuationmeans comprise an actuating rod 8 which is connected to the movingcontact 7 and is actuated by an appropriate actuation and control device10. The actuation and control device can be constituted by a mechanicalor hydraulic or hydraulic-pneumatic or electric actuator; preferably,the use of an electric motor with position control, particularly aservomotor, allows advantages in terms of speed and precision inexecuting the contact opening/closure switching operations.

The disconnection unit 5 comprises a first fixed contact 21 which isconnected to the electric terminal 2, a second fixed contact 22 which isconnected to the fixed contact 7 of the interruption unit 4, a thirdfixed contact 23 which is connected to the fixed contact 7 of theinterruption unit 14, and at least one moving contact 24 which can becoupled to at least one of the fixed contacts 21, 22 and 23.Advantageously, in the embodiment shown in FIG. 2, the disconnectionunit 5 comprises a single moving contact 24 which can be coupled to thethree fixed contacts 21, 22 and 23; said moving contact 24, which isconstituted for example by a blade which has a sector-like profile, isfixed to a rotating shaft 12 substantially at right angles to the axisof the shaft 12. In this manner, the moving contact 24 rotates rigidlywith the shaft 12 and the fixed contacts 21, 22 and 23 lie on its planeof rotation. Clearly, for the sake of simplicity in description, whenthe present description refers to the relative position of the fixedcontact and of the moving contact, reference is always meant to therelative position of the ends of the fixed contact and of the movingcontact that can be coupled thereto.

Alternatively, according to the various application requirements, it ispossible to arrange the fixed contacts 21, 22 and 23 on multiplemutually offset planes, using in this case multiple moving contactswhich are fixed to the rotating shaft 12; in this case, the movingcontacts rotate on different planes and are arranged at an appropriateangle to each other so as to allow electrical connections between thepairs of contacts in the intended sequences. As an alternative, it ispossible to adopt a system with one or more moving contacts whichperform a translatory motion, or other solutions, so long as they arecompatible with the application.

Advantageously, the rotating shaft 12 is actuated by appropriateactuation means, preferably constituted by an electric motor, not shown,which is operatively connected to said shaft 12. In particular, it hasbeen found that the use of a servomotor provides considerable advantagesin terms of operation precision and speed. Alternatively, it is possibleto use mechanical or hydraulic actuation means. Manual actuation meanscan also be provided as an alternative, or as an addition, to the abovedescribed actuation means, particularly for performing emergency manualoperations.

As shown in FIG. 2, the disconnection unit 5 furthermore comprises afourth fixed contact 25 which is grounded. In the case of FIG. 2, thefixed contact 25 is connected to the enclosure 1, which is grounded, andlies on a plane which is different from the plane of the fixed contacts21, 22 and 23. Correspondingly, the device according to the inventionuses a second moving contact 26 which can be coupled to the fixedcontact 25; said moving contact 26, which is for example configured likean L-shaped blade with substantially identical sides, is fixed to theshaft 12 and rotates rigidly therewith on the plane of rotation on whichsaid fixed contact 25 lies.

With this arrangement it is possible to perform various electricswitching operations in a very simple and flexible manner. For example,as shown in FIGS. 3a-3 f, it is possible to have:

the contact 24 simultaneously coupled to the contacts 21, 22 and 23, andthe contacts 26 and 25 uncoupled (FIG. 3a);

the contact 24 coupled to the contacts 21 and 23, and the contacts 22,25 and 26 uncoupled (FIG. 3b);

the contact 24 coupled to the contact 23, the contacts 25 and 26 coupledto each other, and the contacts 21 and 22 uncoupled (FIG. 3c);

the contact 24 coupled to the contacts 22 and 23, and the contacts 21,25 and 26 uncoupled (FIG. 3d);

the contact 24 coupled to the contact 22, the contacts 25 and 26 coupledto each other, and the contacts 21 and 23 uncoupled (FIG. 3e);

the contact 24 coupled to the contacts 21 and 22, and the contacts 23,25 and 26 uncoupled (FIG. 3f).

In addition to these possible configurations it is obviously possible toprovide other switching operations according to the various applicationrequirements.

The solution shown in FIG. 2 is particularly advantageous, in that thelongitudinal axes of the two interruption chambers 4 and 14 aresubstantially mutually aligned and lie at right angles to the rotationaxis of the switching shaft 12; in this manner, the maneuvers of thedisconnection unit occurs by turning the shaft 12 and by turning themoving contacts about the axis of said shaft, while the opening/closureof the interruption units 4 and 14 occurs by virtue of a simpletranslatory motion of the moving contacts along the longitudinal axis ofthe respective interruption chamber. In this manner one achieves optimumdistribution of the space occupied inside the enclosure 1 with asolution which allows extreme flexibility in the electrical switchingoperations that can be performed and in the connections that can beprovided between said device 200 and elements arranged externallythereto, for example loads to be handled, power supply lines, et cetera,as described in detail hereinafter.

Furthermore, the disconnection unit 5 can be arranged so that the axisof the rotation shaft 12 is positioned in a substantially horizontalplane, as shown in FIG. 2, or alternatively, so that the axis of therotation shaft 12 is positioned in a substantially vertical plane, i.e.in a direction which is perpendicular to the axis position of FIG. 2 andto the longitudinal axes of the interruption units; in this case, themotor which drives the shaft 12 may be positioned on the lower part ofthe enclosure 1, with the disconnection contacts correspondigly arrangedinside the enclosure itself.

The device thus conceived, by virtue of its structural compactness andfunctional flexibility, is particularly suitable for use in a substationfor electric power transmission and distribution, both with athree-phase system with single conducting bar and with a three-phasesystem with two conducting bars, according to several applicationconfigurations. Accordingly, the present invention also relates to asubstation for electric power transmission and distribution which isconnected to a three-phase power supply line and is characterized inthat it comprises at least one switchgear device according to theinvention.

In particular, it is possible for example to connect the terminals 11(or 13) and 13 (or 11), respectively in input and in output, to a phaseof a main power supply line and to connect the terminal 2 to a load, forexample a power transformer; or to connect the terminal 11 (or 13) ininput to the power supply phase, the terminal 13 (or 11) to a load, andthe terminal 2 in output to said phase. Another possible alternative isto connect the terminal 2 in input to the power supply phase and theterminals 11 and 13 to two corresponding loads, for example two powertransformers.

A preferred embodiment of a substation with a three-phase single-barsystem, using multiple switchgear devices 200 according to theinvention, is shown in FIGS. 4 and 5. As shown in said figures, eachphase 30 of a three-phase power supply line to which the substation isconnected uses two switchgear devices 200. In particular, a first device200 has a terminal 11 connected in input to the power supply phase 30, aterminal 13 connected in output to a power transformer 31, and aterminal 2 connected, by means of an air-insulated conducting bar 50, tothe corresponding terminal 2 of the second device 200. In turn, thesecond device 200 has its terminals 11 and 13 (or, vice versa, 13 and11) connected respectively in output to the power supply phase 30 and toa power transformer 31. In this manner, there are two sets of threedevices 200 arranged side by side, with a much more compactconfiguration than known substations. This configuration is renderedeven more compact by the fact that, for each of the two sets of threedevices 200, the bushing 40 that belongs to the central device 200 isarranged on a substantially vertical plane, and the other two bushings40 that belong to the devices 200 that are arranged laterally areorientated in mutually opposite directions with respect to the centralbushing.

Another considerable advantage consists of the fact that the devicesused in the substation can be of the single-pole actuation type, inwhich actuation means are provided on each individual phase to performthe disconnecting operation; as an alternative, they can be of the typewith three-pole actuation, in which the energy for performingdisconnection on the three phases of the device is provided by a singleactuation means which is mechanically coupled to the disconnection unitsof each individual phase. An example in this regard is shownschematically in FIGS. 4 and 5, in which each one of the two sets ofthree devices 200 uses a single electric motor 60, preferably aservomotor. In this case, as shown in FIG. 5, the motor 60 is located atone of the devices 200 that are arranged laterally and is connected tothe three corresponding disconnection units by means of a single throughshaft 61 on which the various moving contacts are appropriatelyarranged. As an alternative, the motor 60 can also be arranged on thecentral device 200.

Furthermore, a similar actuation system with single three-pole actuationcan also be used for switching the interruption units; in this case itis in fact sufficient to use two motors 10, arranged at a device 200,each of which is mechanically connected to the actuation rods of themoving contacts of three interruption units arranged side by side.

The substation shown in FIGS. 4 and 5 can furthermore be implemented byusing, for example, an additional set of three devices 200 arranged sideby side and connected sequentially to the first two sets of three, asdescribed above; the connection between the sets of three canfurthermore be provided by using, instead of the bars 30, junctiondevices of the type known in the art, provided with interruption unitswhere necessary. According to another embodiment, the connection betweenpairs of devices 200 can be provided by replacing the containmentbushings 40 and the conducting bars 30 with metal-clad ducts, so as toprovide an even more compact metal-clad structure, with a reducedvertical extension and accordingly with a reduced visual impact. In thismanner it is furthermore possible to eliminate the air-insulated bars,with a consequent advantage from the point of view of maintenance. Inthis case, as in the previously described configurations, the terminals11 and 13 can be accommodated in the respective bushings 41 and 42 andcan also be connected to the power supply phases directly by cablinginstead of by air-insulated means.

If one wishes to provide a substation with a three-phase system with twoconducting bars, the switchgear device 200 can be modified in a verysimple way; in this case it is in fact sufficient to use a fourthconnection terminal and to provide the disconnection unit with anadditional fixed contact, which is connected to the fourth terminal, andoptionally with a further moving contact which can be coupled to saidfixed contact. The fourth terminal can be accommodated in a bushingwhich is arranged proximate to the bushing 40 and is connected to thecorresponding bushing of the second device 200 with a bar 30, asdescribed earlier; in this case also, in order to provide theconnections between the pairs of devices 200 it is possible to usemetal-clad ducts instead of the containment bushings and the conductingbars. The electrical connections in input and in output to the devices200 can furthermore be provided by air-insulated means, by utilizing thebushings, or by providing cabled connections.

The gas-insulated switchgear device thus conceived is susceptible ofmodifications and variations, all of which are within the scope of theinventive concept; all the details may furthermore be replaced withtechnically equivalent elements. In practice, the configurationsconsidered, so long as they are compatible with the specific use, aswell as the individual components, may be any according to therequirements and the state of the art.

What is claimed is:
 1. A gas-insulated switchgear device for high- andmedium-voltage applications, comprising an enclosure which contains adisconnection unit which is electrically connected to a first electricterminal and is arranged in the enclosure in a substantially centralposition, and a first interruption unit and a second interruption unitwhich are connected electrically to the disconnection unit and,respectively, to a second electric terminal and a third electricterminal, said first and second interruption units being arrangedmutually opposite with respect to the disconnection unit, wherein saidfirst and second interruption units each comprise an interruptionchamber which accommodates a fixed contact and a moving contact.
 2. Theswitchgear device according to claim 1, wherein the disconnection unitcomprises a first fixed contact, a second fixed contact and a thirdfixed contact which are respectively connected to said first terminaland to said first and second interruption units, and at least one movingcontact which can be coupled to at least one of said fixed contacts. 3.The switchgear device according to claim 2, comprising a first movingcontact which can be coupled to said first, second and third fixedcontacts, said moving contact being fixed to a rotary operating elementand rotating rigidly therewith, said fixed contacts lying on a rotationplane of said,moving contact.
 4. The switchgear device according toclaim 3, wherein the first moving contact is constituted by a bladewhich has a sector-shaped profile, is keyed on said rotary operatingelement and is substantially perpendicular to a rotation axis of saidoperating element.
 5. The switchgear device according to claim 2,wherein the disconnection unit comprises a fourth fixed contact which isgrounded.
 6. The switchgear device according to claim 5, wherein thedisconnection unit comprises a second moving contact which can becoupled to the fourth fixed contact, said second moving contact beingfixed to the operating element and rotating rigidly therewith, thefourth fixed contact being arranged on the rotation plane of the secondmoving contact.
 7. The switchgear device according to claim 5, whereinthe first moving contact and the second moving contact are fixed to theswitching element so as to rotate on two different rotation planes. 8.The switchgear device according to claim 4, wherein the rotary operatingelement is actuated by an electric motor.
 9. The switchgear deviceaccording to claim 4, wherein said moving contact which is accommodatedin the interruption chamber is operatively controlled by actuationmeans, a longitudinal axis of said interruption chamber being arrangedsubstantially at right angles to the rotation axis of the operatingelement.
 10. The switchgear device according to claim 9, wherein saidactuation means comprise a servomotor.
 11. The switchgear deviceaccording to claim 4, wherein the rotary operating element is positionedso that its rotation axis lies in a substantially horizontal plane. 12.The switchgear device according to claim 4, wherein the rotary operatingelement is positioned so that its rotation axis lies in a substantiallyvertical plane.
 13. An electric power transmission and distributionsubstation, suitable to be connected to a three-phase power supply line,comprising at least one switchgear device according to claim
 1. 14. Thesubstation according to claim 13, comprising, for each phase of thepower supply line, a first switchgear device and a second switchgeardevice, the first device having a first electric terminal which isconnected to a first terminal of the second device, a second electricterminal which is connected in input to a power supply phase, a thirdelectric terminal which is connected to a first power transformer, saidsecond device having a second electric terminal which is connected inoutput to the power supply phase and a third electric terminal which isconnected to a second transformer.
 15. The substation according to claim14, wherein the first, second and third electric terminals arerespectively accommodated in a first, second and third bushingrespectively, and in that the first terminal of the first device isconnected to the first terminal of the second device by means of anair-insulated conducting bar.
 16. The substation according to claim 15,wherein the switchgear devices are divided into two sets of threedevices arranged side by side, the first bushing of the device that ispositioned centrally in the set of three being arranged on asubstantially vertical plane, the first bushings that belong to the twodevices of the set of three that are positioned laterally beingorientated in mutually opposite directions with respect to said verticalplane.
 17. The substation according to claim 14, wherein the firstterminal of the first device is connected to the first terminal of thesecond device by means of a metal-clad duct.
 18. The substationaccording to claim 1, comprising, for a set of three switchgear devices,a single electric motor which is suitable to actuate the threecorresponding disconnection units.